the concentration of Fe2+(aq) solution is a.bcd mol/L.

Question

An iron ore sample containing a mixture of compounds containing Fe3+ (aq) and Fe2+ (aq) is dissolved in acid, which reduces all of the Fe3+ (aq) to Fe2+ (aq). The acidic solution is titrated with KMnO4(aq). If 10.0 mL of Fe2+ (aq) solution is titrated with 0.0167 L of 0.0813mol/L KMnO4(aq), the concentration of Fe2+(aq) solution is a.bcd mol/L.

Answer 1

This following answer provides the calculation for the concentration of Fe²⁺ in the final solution after all the Fe³⁺ has been reduced. It does not provide the concentration of Fe²⁺ in the original sample.

5Fe²⁺ + MnO₄^- + 8H⁺ ==> Mn²⁺ + 5Fe³⁺ + 4H₂O ... balanced redox equation

mols MnO₄^- used = 0.0167 L x 0.0813 mol/L = 0.00140 mols MnO₄^-

mols Fe²⁺ present = 0.00140 mols MnO₄^- x 5 mols Fe²⁺ / mol MnO₄^- = 0.00680 mols Fe²⁺

Volume of solution = 10.0 ml x 1 L/1000 ml = 0.0100 L

Concentration of Fe²⁺ = 0.00680 mols / 0.0100 L = 0.6789 mol/L = 0.679 mol/L

a = 0

b = 6

c= 7

d = 9